Correlation between preoperative systemic immune-inflammatory indexes and the prognosis of gastric cancer patients.

Objective: The aim of this study is to explore the potential value of high preoperative systemic immune-inflammation index (SII) expression in the prognosis of patients with gastric cancer (GC) by meta-analysis.

Materials And Methods: The major databases were searched to screen relevant clinical studies on the prognostic value of SII in gastric cancer (GC) patients, published from the establishment of the database to May 2022. RevMan 5.3 was utilized to perform a meta-analysis of relevant data. The differences in age, tumor size, differentiation degree, tumor-node-metastasis (TNM) stage, overall survival (OS), neutrophil to lymphocyte ratio (NLR), and platelet to lymphocyte ratio (PLR) between the high SII expression group (H-SII) and the low SII expression group (L-SII) were compared. Heterogeneity was assessed by Cochran's Chi-square test.

Results: A total of 16 studies with 5,995 GC patients were included. Compared with the L-SII group, the proportion of patients older than 60 years in the H-SII group was markedly higher (OR=0.85, 95% CI: 0.75-0.97; Z=2.45, p=0.01); the proportion of patients with tumor size larger than 5 cm increased (OR=2.18, 95% CI: 1.69-2.81; Z=6.03, p<0.00001); the proportion of patients with TNM stage ≥T3 increased (OR=2.41, 95% CI: 1.89-3.08; Z=7.06, p<0.00001); overall survival (OS) decreased (OR=-23.92, 95% CI: -37.57 to -10.26; Z=3.43, p=0.0006); the 5-year survival rate (SR) decreased markedly (OR=0.39, 95% CI: 0.24-0.64; Z=3.81, p=0.0001); the proportion of patients with high NLR expression was increased (OR=22.19, 95% CI: 10.66-46.18; Z=8.29, p<0.00001); and the proportion of patients with high PLR expression was also markedly increased (OR=15.97, 95% CI: 8.57-29.75; Z=8.73, p<0.00001).

Conclusions: A high preoperative SII was an independent risk factor for poor prognosis in GC patients.